The reference electrode was placed distally. In the A series (Fig. 1), the active and reference electrodes for channel 1 were plastic-mounted bipolar electrodes (surface disks 3 cm apart); the active recording electrode was placed at the apex of the “V” between the first and second metacarpal bones, and the reference electrode was placed distally. In the B series (Fig. 2), the active and reference electrodes for channel 1 were rings mounted on the thumb, with

the active electrode proximal and the reference electrode 3 cm distal. Inhibitors,research,lifescience,medical Figure 1 Assembly for the realization of the A series. The image was made with the forearm pronated for better visualization. The nerve conduction data were obtained with the forearm supinated. Figure 2 Assembly for the realization of the B series.

We considered the measurement to be positive for variation in the Inhibitors,research,lifescience,medical upper limbs when a SNAP was obtained on channel 1, whereas channel 2 showed a clear LACN SNAP (Fig. 3, ​,4).4). We believe that the SNAP captured on channel 1, an area normally Inhibitors,research,lifescience,medical supplied by the RSN, originates from the variant LACN. Figure 3 An example of an upper limb positive in the A series. The upper curve represents the channel 1, with the SNAP obtained in the dorsum of the hand. The lower curve represents the channel 2 with the LACN SNAP obtained by standard technique. Figure 4 An example of an upper limb positive in the B series. The upper curve represents the channel 1, with Inhibitors,research,lifescience,medical the SNAP obtained in the first finger. The lower curve represents the channel 2 with the LACN SNAP obtained by standard technique. Even with the precautions taken in the stimulation and in the exclusion of patients with motor artifact,

costimulation of RN remains as a possible pitfall of this technique. Results Of the 50 patients in the A series, 10 were male (20%) and 40 female (80%). We found six patients (12%) who Gamma-secretase inhibitor tested positive for the RSN–LACN anatomic variation; all of them were females. We found two patients (4%) who tested positive for the variation in both upper limbs. Of Inhibitors,research,lifescience,medical the 100 upper limbs studied, we observed eight (8%) that were positive for the variation. All the four patients with unilateral variation showed variation on the left side. The SNAP amplitude obtained in channel 1 in the eight positive limbs ranged from 0.74 to 10.6 μV, with an average of 5.2 μV. Of the 50 new patients in the B series, 10 were male (20%) and 40 female (80%). We found 11 patients (22%) who tested positive for the RSN–LACN anatomic variation; all of them were females. We did not find bilateral variation in the B series. Of the 100 upper limbs studied, we observed 11 (11%) that were positive for the variation. In 11 patients with unilateral variation, six (54.5%) showed the variation on the left side, and five (45.5%) had the variation on the right side. The SNAP amplitude obtained in channel 1 in the 11 positive limbs ranged from 0.70 to 6.